Re: [RFC/PATCH] cgroup swap subsystem [message #28031] |
Thu, 06 March 2008 08:33 |
KAMEZAWA Hiroyuki
Messages: 463 Registered: September 2006
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Senior Member |
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On Thu, 06 Mar 2008 11:20:17 +0300
Pavel Emelyanov <xemul@openvz.org> wrote:
> KAMEZAWA Hiroyuki wrote:
> > On Wed, 05 Mar 2008 17:14:12 +0300
> > Pavel Emelyanov <xemul@openvz.org> wrote:
> >>> Strongly agree. Nobody's interested in swap as such: it's just
> >>> secondary memory, where RAM is primary memory. People want to
> >>> control memory as the sum of the two; and I expect they may also
> >>> want to control primary memory (all that the current memcg does)
> >>> within that. I wonder if such nesting of limits fits easily
> >>> into cgroups or will be problematic.
> >> This nesting would affect the res_couter abstraction, not the
> >> cgroup infrastructure. Current design of resource counters doesn't
> >> allow for such thing, but the extension is a couple-of-lines patch :)
> >>
> > IMHO, keeping res_counter simple is better.
> >
> > Is this kind of new entry in mem_cgroup not good ?
> > ==
> > struct mem_cgroup {
> > ...
> > struct res_counter memory_limit.
> > struct res_counter swap_limit.
> > ..
> > }
>
> I meant the same thing actually. By "nesting would affect" I
> meant, that we might want to make res_counters hierarchical.
>
> That would kill two birds with one stone - we will make a true
> hierarchical memory accounting and let charging of two counters
> with one call.
Hierarchical res_counter makes sense.
Making it in simple/reasonable style will be our challenge.
Thanks,
-Kame
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Re: [RFC/PATCH] cgroup swap subsystem [message #28033 is a reply to message #28031] |
Thu, 06 March 2008 08:38 |
Pavel Emelianov
Messages: 1149 Registered: September 2006
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Senior Member |
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KAMEZAWA Hiroyuki wrote:
> On Thu, 06 Mar 2008 11:20:17 +0300
> Pavel Emelyanov <xemul@openvz.org> wrote:
>
>> KAMEZAWA Hiroyuki wrote:
>>> On Wed, 05 Mar 2008 17:14:12 +0300
>>> Pavel Emelyanov <xemul@openvz.org> wrote:
>>>>> Strongly agree. Nobody's interested in swap as such: it's just
>>>>> secondary memory, where RAM is primary memory. People want to
>>>>> control memory as the sum of the two; and I expect they may also
>>>>> want to control primary memory (all that the current memcg does)
>>>>> within that. I wonder if such nesting of limits fits easily
>>>>> into cgroups or will be problematic.
>>>> This nesting would affect the res_couter abstraction, not the
>>>> cgroup infrastructure. Current design of resource counters doesn't
>>>> allow for such thing, but the extension is a couple-of-lines patch :)
>>>>
>>> IMHO, keeping res_counter simple is better.
>>>
>>> Is this kind of new entry in mem_cgroup not good ?
>>> ==
>>> struct mem_cgroup {
>>> ...
>>> struct res_counter memory_limit.
>>> struct res_counter swap_limit.
>>> ..
>>> }
>> I meant the same thing actually. By "nesting would affect" I
>> meant, that we might want to make res_counters hierarchical.
>>
>> That would kill two birds with one stone - we will make a true
>> hierarchical memory accounting and let charging of two counters
>> with one call.
>
> Hierarchical res_counter makes sense.
> Making it in simple/reasonable style will be our challenge.
I have this in my TODO list. Since this is not so urgent, then if you
don't mind I can prepare the patches next week - after I set the git
tree up. This change doesn't seem that big.
> Thanks,
> -Kame
>
>
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Re: Re: [RFC/PATCH] cgroup swap subsystem [message #28037 is a reply to message #28034] |
Thu, 06 March 2008 08:50 |
Pavel Emelianov
Messages: 1149 Registered: September 2006
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Senior Member |
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Paul Menage wrote:
> On Thu, Mar 6, 2008 at 12:38 AM, Pavel Emelyanov <xemul@openvz.org> wrote:
>> > Hierarchical res_counter makes sense.
>> > Making it in simple/reasonable style will be our challenge.
>>
>> I have this in my TODO list. Since this is not so urgent, then if you
>> don't mind I can prepare the patches next week - after I set the git
>> tree up. This change doesn't seem that big.
>>
>
> The change that you're referring to is allowing a cgroup to have a
> total memory limit for itself and all its children, and then giving
> that cgroup's children separate memory limits within that overall
> limit?
Yup. Isn't this reasonable?
Without this, if I'm a task in a 1GB limited cgroup, I can create a new
one, set 2GB limit and spawn a kid into it (or move there myself) and be
happy with 2GB of memory... With the proposed change, even if I set a 2GB
for a subgroup it will not pass _my_ (1GB) limit.
> Paul
>
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